fix(trial): use propagated gomega to improve debuggability.

[Electronic-Waste]

What this PR does / why we need it:

As I described in #2431, a propagated gomega.Gomega will improve the debuggability of the UTs.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #2431

Checklist:

• Docs included if any changes are user facing

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[Electronic-Waste]

/rerun-all

[Electronic-Waste]

I've replaced func() bool with func(g gomega.Gomega) in the UTs of Trial Controller.

PTAL if you have time👀 @kubeflow/wg-automl-leads